You can't, at least not without additional hardware. Your Famicom is only going to output an analog video signal via RF while the RF input on your television is only going to support a digital signal.
So your options are either (a) an RGB mod to allow your Famicom to output an RGB signal which can then be converted to HDMI, or (b) an analog-to-digital signal converter. Option A (and specifically I'm thinking of the NESRGB mod which I recently installed in my own NES) will give you a much MUCH cleaner image but will ultimately be more expensive (due to the requirement of a further RGB-to-HDMI converter), and requires soldering. Option B is simpler and cheaper but does nothing to improve the image (and it may even look worse due to the nature of LCD screens).
Both options will introduce a bit of lag, option A due to the RGB-to-HDMI converter and option B due to the analog-to-digital converter. How much lag is going to depend upon the quality of the converter you choose.
Option C is to get a TV with S-video input, install the NESRGB into your Famicom, then connect the modded Famicom directly to the TV via S-video. You'll get the benefits of better video quality with no lag.